The invention relates to a control valve, especially for an internal combustion engine, for the controlled recycling of exhaust gases to the fresh gas of the internal combustion engine, with the distinguishing features in the introductory portion of claim 1.
A control valve for recycling exhaust gases into the intake manifold of an internal combustion engine of this type is known (DE 42 04 434 C2), for which the first valve part may be constructed as a flat slide valve, which interacts with a flat seat of the outlet opening of the exhaust gas pipeline, the flat seat of the outlet opening and the flat slide valve being disposed in an expansion of the exhaust gas channel of the valve housing. The flat slide valve is moved over a rod by control equipment, such as electromagnetic control element, against a spring in the opening direction, the spring, in the unactivated position of the control equipment, bringing the flat slide valve into the closed position, so that exhaust gas is not recycled then. The flat seat and flat slide valve are made from materials with low friction properties, so that the adjusting force required is small. The flat slide valve contains only a slide valve opening, which, in the open position, is caused to overlap the outlet opening, the slide valve opening determining the cross section of flow of the outlet opening. Alternatively, the exhaust gas can also be recycled to the individual cylinders of the internal combustion engine over individual exhaust gas pipelines. In the latter case, the flat slide valve has a slide valve opening for each individual exhaust gas pipeline, in which there is an outlet opening. The flat slide valve is shifted in the direction of its areal extent and transversely to the advancing exhaust gas by means of the rod over the control device between the open position and the closed position. The flat slide valve rests two-dimensionally on the end of the exhaust gas pipeline, which is directed transversely thereto, this end containing the outlet opening. The exhaust gas, supplied into the exhaust gas channel, upstream from the flat slide valve, strikes the latter transversely and, in the open position of the flat slide valve, after passing through the slide valve opening, reaches the exhaust gas pipeline directed in exactly the same direction. Admittedly, in said publication, it is noted that the flat slide valve, which is actuated back and forth translatorily, can also be constructed as a rotating flat slide valve. However, no information is provided concerning the arrangement and rotary actuation of such a flat slide valve. In particular, this known flat slide valve has the disadvantage that, when in operation, soot and similar particles can deposit, cake on and thus adhere to the flat seat with the outlet opening, as well as to the flat slide valve with the slide valve opening of the latter and the adjoining areas and affect the satisfactory operation of the control valve and, after some time, make such an operation completely impossible. From this, it follows that, already after a relatively short period of use of the control valve, the adjustment of the flat slide valve becomes difficult. Because of this, a control device is required, which makes relatively large adjusting forces possible. Such a control device requires relatively much space, is heavy and expensive.
It is an object of the invention to configure a control valve of the type mentioned above as a rotary slide valve of such a type, that a slight rotational adjusting force is required for adjusting the rotatable part of the valve. As a result, the control device can be configured small, compact, light and relatively inexpensive and, furthermore, not only is slight friction ensured between the parts of the valve, which can be rotated relative to one another, and smooth running during the rotational adjustment, but also a permanent collection of soot or of similar particles, which could affect the mode of operation, is counteracted.
Pursuant to the invention, this objective is accomplished for a control valve of the type mentioned above by the distinguishing features of claim 1. By these means, it is achieved that the surfaces, on which the two parts of the valve are in contact with one another and slide during the adjustment between the closed position and the open position, are reduced to narrow surfaces. This enables the two parts of the valve to move easily relative to one another and, with that, to be adjusted quickly. Furthermore, any wear is only slight. The ease of the adjusting motion makes it possible to use a control device, which is small, light, compact and relatively inexpensive. It is furthermore of advantage that, because of the narrow surfaces of the one valve part, on which the other valve part rests and slides during the relative adjustment, edges, which may be relatively sharp, are created in the case of the narrow surfaces and, during the sliding motion, act similarly to a scraping tool in such a manner, that any adhering particles, such as soot or the like, are shaved off, scratched off or removed in some other way during the sliding motion, before they can cake on firmly. Removal of these particles by chipping off is also favored by these means. Furthermore, the inventive control valve is small, compact, light and relative inexpensive. The small construction and the few individual parts used result in a low weight and small manufacturing costs. Furthermore, the control valve is operationally reliable and has a long service life. It is furthermore of advantage that the control valve is not only insensitive to contamination, but also makes possible a highly accurate adjustment. Furthermore, the valve has only slight leaks and the adjusting force or torque, required actuate the valve, remains constant over the service life of the control valve.
Further, special distinguishing features and developments of the invention arise out of the dependent claims.
Further details and advantages of the invention arise, moreover, out of the following specification.
The complete wording of the claims is not given above merely to avoid unnecessary repetition. Instead, it is merely referred to by reference to the claims. However, by such reference, they are to be regarded as having been disclosed at this place explicitly as essential elements of the invention. Moreover, all distinguishing features mentioned above or below in the specification, as well as the distinguishing features, which may be inferred only from the drawings, are further components of the invention, even if they are not emphasized especially and, in particular, if they are not mentioned in the claims.